The increasing spread of computer technology and its application to all aspects of daily life has led to new and complex issues and problems. With the advent of broadband access to the Internet, an increasing number of content providers are using multicast technologies to deliver their content to subscribers. This usually involves establishing a continuous data flow between the content source and an end user device with the data flow containing the content. More often that not, such content takes the form of multimedia data with both voice and video content encoded in the data flow.
To simplify matters for end users, these data flows can be accessed by end user devices such as set top boxes. This technology has been used to deliver not only varied multimedia content but even regular television signals. Such TV signals are quite amenable to multicast technology as such signals are essentially broadcast to multiple end user devices simultaneously. All an end user device has to do to receive a TV signal multicast over the Internet is to receive the data flow emanating from the content source.
However, to prevent unauthorized access to these multicasts, content providers currently encrypt the multicast data at the source end. Legitimate end users can receive the data flow and are provided with appropriate decryption keys to decrypt the data flow. Such end-to-end encryption unfortunately can be inconvenient. Specifically, encryption and decryption capabilities are required at each end of the data flow link. Furthermore, the encryption and decryption keys and algorithms need to be periodically replaced or updated to prevent unauthorized users elements from breaking into the system. Clearly, such a system for preventing access to multicast data is inconvenient and can be costly. It is an object of the present invention to provide alternatives which overcomes or mitigates the disadvantages of the prior art.
It should be noted that the term data transmission unit (DTU) will be used in a generic sense throughout this document to mean units through which digital data is transmitted from one point in a network to another. Thus, such units may take the form of packets, cells, frames, or any other unit as long as digital data is encapsulated within the unit. Thus, the term DTU is applicable to any and all packets, cells, frames, or any other units that implement specific protocols, standards or transmission schemes. It should also be noted that the term digital data will be used throughout this document to encompass all manner of voice, multimedia content, video, binary data or any other form of data or information that has been digitized and that is transmitted from one point in a network to another.